Heretofore, ion implantation has been utilized for several beneficial purposes in connection with semiconductor devices. Illustratively, He ions have been implanted through an insulator layer of SiO.sub.2 to an interface with a Si substrate for neutralizing undesirable charge states at the interface. Further, He ions have been implanted into a layer of SiO.sub.2 adjacent a semiconductor body to neutralize free Na ions in the SiO.sub.2 layer which are detrimental to the operation of the semiconductor device.
Contrary to the premise of this invention, it has been reported in the literature that the implantation of ions into a thin insulator film decreases the dielectric breakdown strength of the film. It is theorized for understanding the premise of this invention that the noted decrease in dielectric breakdown strength reported in the literature may have occurred for one or more of the following reasons: the implanted ions were electron traps in the dielectric insulator; the implantation partially decomposed the lattice of the insulator; and the implantation degraded the relatively smooth interface between the insulator and its electrical contacts thereon.
It has been discovered, for the practice of this invention, that the implanting of specific ions into a film of amorphous SiO.sub.2 insulation at a particular energy and dosage, in conjunction with an annealing treatment of the film, improves the dielectric breakdown strength of the film.